Communications systems often involve multiple elements networked together. The network elements, e.g., switches, routers, and signal transfer points, are often required to operate in a manner that complies with one or more standards, e.g., communications protocol standards, which may ser signal timing, fault handling, and message requirements. As networks and communications protocols become more advanced, compliance and interoperability testing becomes more difficult. Realistic testing of network components to determine interoperability and standards compliance in situations approaching actual network circumstances has proven to be a difficult task because of the complexity of the chain of events which must be tested for and problems associated with obtaining accurate event timing information. Some of the difficulties associated with testing are a function of differences, e.g., inaccuracies, in the clocks associated with various network components which monitor for events and provide time stamps corresponding to the time of the detected events. In accuracies in network component clocks make it difficult to accurately compare and sequence events detected at different points in a network to determine if they occurred in the proper order and within specified times of one another.
IP based networks as well as other communications networks often share the above described interoperability and standards compliance testing problems. A well known network in which such testing problems are frequency encountered is the Public Switched Telephone Network (PSTN). Telephone service providers worldwide use signaling protocols, e.g., Signalling System 7 (SS7) protocol to provice the signaling required for communication systems, e.g., SS7, may exist between Service Switching Points (SSPs), Service Control Points, (SCPs), and Signalling Transfer Points (STPs) in a communications network. The SSPs are end sources and destinations for the SS7 messages. The SCPs provide database functions. The STPs switch the SS7 messages on their paths as they travel throughout the system.
Typically, STPs are deployed in mated pairs, providing redundancy, and enabling the switching service to be maintained even if one STP should fail. Mated pairs of STPs may be interconnected throughout the SS7 network. A mated pair of STPs may connect to a set of STPs, to SCPs, that provide database functions, or to another mated pair of STPs. One commonly used STP interconnection setup is called a QUAD configuration consisting of 2 sets of mated pairs. The total SS7 communications network may be operated by a single organization or may be a composite of smaller SS7 networks operated by different organizations. Interfaces between SS7 networks allow a Local Exchange Carrier to send its signaling traffic over another carrier's network. This is becoming increasingly important in the United States as regulatory bodies are encouraging competition between Local Exchange Carriers by requiring incumbent carriers to open their network to the signaling traffic of competitors, in exchange for being granted rights to provide long-distance services. Different carriers may source their STPs from different vendors or configure their STPs differently; this leads to a need to test the interoperability of STPs from different carriers. A single carrier may source STPs from different vendors, for reasons such as risk management or encouraging competition between vendors for the supply equipment. Typically, a single carrier will often deal with three or more different vendors of STPs. Each STP vendor regularly issues new releases of the software and hardware for their STPs, e.g., multiple times per year. Thus, a communications system may include a composite of STPs from many vendors, with multiple hardware and software versions. For a carrier to ensure that the signaling network continues to operate correctly, it needs to regularly test STP quad interoperability. Thus carriers have a strong need for performing interoperability and conformance testing of STPs on a regular basis to ensure that the reliability of their system is maintained.
The testing to be performed on STPs is complicated due to the nature of the SS7 protocol, time consuming, labor intensive, and (for the most part) mundane. The labor intensive nature of the analysis of the testing as currently performed results in significant cost for the communications provider. The characteristics described above make STP Quad interoperability testing a good candidate for automation. In view of the above discussion, it is clear that a need exists in the industry for a better system and method to perform STP testing, e.g., interpretability testing. Preferably, one or more testing steps should be automated thereby reducing the time required to perform the testing and increasing test accuracy.